This invention relates to a magnetic recording medium and a magnetic recording method, more particularly to a thermo-magnetic recording medium and method by which a thermal pattern as input signals is appropriately converted into a magnetic signal pattern. Further, this invention relates to a demagnetizing method for a thermo-magnetic recording operation.
In magnetic recording methods, a magnetic latent image is formed in a magnetic material by magnetization and is then made visible by magnetic toner particles, namely, magnetization detection type coloring particles which include magnetic particles in macromolecular resin, for instance, and which are affected by a magnetic field. The visible image thus obtained is transferred onto a sheet or the like by an electrostatic or magnetic method, and is then fixed by heat or pressure.
The same process is again carried out when the magnetic latent image carrier, namely, the magnetic recording medium, after being subjected to magnetic toner removal, is directly moved to the next developing cycle, or when, with the magnetic latent image erased, a new latent image has been formed.
In the above-described magnetic recording method, the magnetic latent image is, in general, formed by magnetization with a recording current being allowed to flow in the magnetic head adjacent to the magnetic recording medium according to the image signals.
In the case where such a magnetic head is used to form a magnetic latent image over the entire width of the magnetic recording medium, in general, single or plural printing sections for magnetization, i.e., magnetic recording tracks with recording gaps are provided, and a magnetic recording operation is carried out by the combination of a recording operation (main scanning) in the direction of movement of the magnetic recording medium and a transverse scanning operation (auxiliary scanning) performed perpendicularly to the aforementioned direction.
According to this method, an accurate drive and control method for maintaining the auxiliary scanning intervals constant is required, or it is necessary to move the magnetic recording medium at a high speed to reduce the scanning time, or to move the magnetic recording medium at low speed to form an image through development and transfer. That is, a precise and expensive drive and control method including various operational modes is required.
For such a scanning magnetic head recording operation, a method has been proposed in which a so-called multi-magnetic head array, in which magnetic recording tracks are provided over the entire image width with high density so as to meet the necessary resolution of the reproduced image, is used to record the image one picture element by one picture element as the magnetic recording medium is moved.
With this multi-magnetic head array, in order to attain sufficient resultion of the reproduced image, it is necessary to provide thin tracks (less than about 100 .mu.m in width) at intervals of about 100 .mu.m.
Furthermore, in order to reduce the recording current, it is necessary to provide coils of plural turns for these tracks; that is, small and intricate parts are necessary. In addition, because of the electromagnetic interference between adjacent tracks, the realization of such a multi-magnetic-head array is considerably difficult.
In erasing the magnetic latent image, it has been proposed to apply AC magnetic field to the magnetic recording medium provided with the magnetic latent image.
In this case, one may consider utilizing an erasing magnetic head to erase the magnetic latent image on the magnetic recording medium. In general, the erasing magnetic head is energized by a high frequency power source and has a long track width.
Further, in the above-described AC magnetic field application method in which a magnetic head having a long track width is used, the head must be considerably high in uniformity in the longitudinal direction in order that it may be brought in satisfactorily close contact with the recording medium, with a result that the head becomes high in manufacturing cost.